The present invention relates to a digital broadcast channel reception system. More particularly, the invention relates to a portable digital broadcast channel reception system that allows watching a digital broadcast on a mobile terminal such as a portable cellular telephone or a personal digital assistance (PDA).
In Japan, digital broadcasting is now promoted and CS and BS digital broadcasting services are carried out. Moreover, satellite digital audio broadcasting, terrestrial digital television broadcasting, and terrestrial digital audio broadcasting services are planned to be implemented in near future.
In the terrestrial digital television broadcasting, an Orthogonal Frequency Division Multiplexing (OFDM) method is used. In the OFDM method, a transmission bandwidth allocated for transmission line coding is divided into 13 segments which are, in turn, classified into a maximum of three hierarchies. For each hierarchy, parameters for required transmission characteristics such as a coding rate for codes within carrier modulation (DQPSK, QPSK, 16QAM, 64QAM) are specified. As for one central segment of the 13 segments, it is possible to receive the broadcast service, using a portable terminal or the like receiving that segment only (Journal of the Institute of Image Information and Television Engineers (ITE), Vol. 53, No.11, pp. 1456-1459 (1999)).
In the terrestrial digital audio broadcasting for audio priority over video, three center segments of the 13 segments are used (Journal of the ITE, Vol. 53, No. 11 pp. 1479-1484 (1999)).
In the case of the terrestrial digital audio broadcasting also, as for one central segment of the three segments, it is possible to receive the broadcast service, using a portable terminal or the like receiving that segment only.
As for information encoding methods for digital broadcasting services, Moving Picture Experts Group (MPEG) 1, MPEG2, and MPEG4 are thought to be used for data encoding (Journal of the ITE, Vol. 52, No. 11 pp. 1551-1553 (1998)).
In the case of satellite and terrestrial digital audio broadcasting, MPEG4 audio encoding is thought to be used for audio encoding (Journal of the ITE, Vol. 52, No. 11 pp. 1549-1550 (1998)).
As for terminals capable of partially receiving the service of terrestrial digital broadcasting, those that can receive the broadcasting service while moving in a compatible mode with portable cellular telephone or mobile terminal functionality are expected to be used (Journal of the ITE, Vol. 52, No. 11 pp. 1539-1545 (1998)).